Method and apparatus for fast assistive transmission operation

ABSTRACT

A method for use in a wireless transmit/receive unit (WTRU) for receiving data over physical downlink shared channels from different cells, monitoring physical downlink control channels of a first cell for downlink control information associated with the WTRU, and recovering data from the physical downlink control channel in response to the downlink control information.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/166,364 filed on May 27, 2016, which is a continuation of U.S. patentapplication Ser. No. 14/518,573, filed Oct. 20, 2014, which issued onMay 31, 2016 as U.S. Pat. No. 9,356,750, which is a continuation of U.S.patent application Ser. No. 13/248,343, filed on Sep. 29, 2011, whichissued on Oct. 21, 2014 as U.S. Pat. No. 8,867,442, which claims thebenefit of U.S. Provisional Application No. 61/389,102, filed on Oct. 1,2010; U.S. Provisional Application No. 61/480,996, filed on Apr. 29,2011; and U.S. Provisional Application No. 61/523,007, filed on Aug. 12,2011, the contents of which are hereby incorporated by reference herein.

BACKGROUND

The Third Generation Partnership Project (3GPP) wideband code divisionmultiple access (WCDMA) initial release (R99) includes mechanisms forsoft combining on the downlink for the dedicated channels (DCH). In softcombining operations, the wireless transmit/receive unit (WTRU) receivesthe same information via multiple Node Bs and combines the receivedinformation at the soft bit level. This was possible due to the constantover-the-air bit rate that was transmitted simultaneously across allNode Bs. When high-speed downlink packet access (HSDPA) was introducedin Release 5, this approach could no longer work in this context,because the instantaneous bit rate in HSDPA is determined locally ateach Node B based on instantaneous channel measurements. The throughputincrease obtained by using instantaneous channel measurements surpassedthe macro-diversity gain obtained by soft combining.

More recently, the WCDMA standards in Release 8 introduced dual-cellHSDPA operations (DC-HSDPA), where the WTRU receives data simultaneouslyfrom two cells of the same Node B over adjacent frequencies in the sameradio band. This approach allows doubling the WTRU downlink data rate(while also using double the bandwidth). In Release 9 and Release 10 ofthe standards, the concept was extended to support multi-band operationsand up to four simultaneous downlink carriers. While this approachimproves the WTRU throughput across the cell, it does so at the expenseof additional bandwidth and does not provide significant system-widegain. For WTRUs experiencing cell-edge conditions, other techniques mayprovide improved coverage while not necessitating the additionalbandwidth.

Other approaches have been proposed to take advantage of the presence ofthe second or multi-receiver chain (necessary for multi-cell HSDPA,e.g., 2C/4C HSDPA, operations) to receive over at least two differentcells, but in the same frequency to improve the reception throughput atthe cell edge or the sector edge, potentially increasing spectralefficiency. This gain may be realized by using multipoint (ormulti-cell) transmission/reception of data from geographically separatedcells (points) in the same frequency and/or different frequencies. Thisform of operation is referred to as multipoint HSDPA operation. It isnoted that single-frequency DC-HSDPA (SF-DC-HSDPA) is one exampleembodiment of multipoint HSDPA.

Approaches to provide throughput gains for multipoint HSDPA may beloosely grouped into four different categories (source switching, softcombining, source multiplexing, or multi-flow aggregation) based on thenumber of different transport blocks the WTRU may receive at eachtransmission time interval (TTI). In source switching, the WTRU receivesdata from a single source at a time, but may receive data from multiplesources over time. In soft combining, the WTRU receives the same datafrom multiple sources and combines the soft information for improveddetection performance. In source multiplexing, the WTRU receivesdifferent data from multiple sources simultaneously. All of theseapproaches attempt to improve WTRU throughput at the cell edge or thesector edge.

Depending on the mode of the multipoint DC-HSDPA operations, the WTRUhas to perform a number of tasks to demodulate the data carried on thehigh speed physical downlink shared channel (HS-PDSCH). To do so at areasonable complexity, it is preferable for the Node B to transmit basicinformation to help the WTRU decide what part of the code space todecode, and how it is modulated and encoded in general. This signalingand the associated WTRU actions may take different forms, depending onthe multipoint HSDPA mode of operation.

SUMMARY

A method for coordinating discontinuous reception (DRX) operationbetween a primary serving cell and a secondary serving cell includesconfiguring DRX parameters for the primary serving cell and thesecondary serving cell, performing a radio interface synchronizationprocedure to align a connection frame number (CFN) in both the primaryserving cell and the secondary serving cell, and coordinating DRXreception patterns for the primary serving cell and the secondaryserving cell using the aligned CFN.

A method for notification-based DRX activation or deactivation includestransmitting an activation or deactivation order for a primary servingcell from a Node B of the primary serving cell to a wirelesstransmit/receive unit (WTRU), transmitting a corresponding DRXactivation or deactivation notification from the Node B of the primaryserving cell to a serving radio network controller (SRNC), receiving aDRX activation or deactivation command at a Node B of a secondaryserving cell from the SRNC, and transmitting an activation order for thesecondary serving cell from the Node B of the secondary serving cell tothe WTRU.

A method for notification-based DRX activation or deactivation includestransmitting a DRX activation or deactivation request from a Node B of aprimary serving cell to a serving radio network controller (SRNC),receiving a DRX activation or deactivation grant at the primary Node Bfrom the SRNC, and transmitting a DRX activation or deactivation orderfor the primary serving cell and a secondary serving cell from theprimary Node B to a wireless transmit/receive unit (WTRU).

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawings,wherein:

FIG. 1A is a diagram of an example communications system in which one ormore disclosed embodiments may be implemented;

FIG. 1B is a diagram of an example wireless transmit/receive unit (WTRU)that may be used within the communications system illustrated in FIG.1A;

FIG. 1C is a diagram of an example radio access network and an examplecore network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 is a diagram showing an operation mode of the identical signalbeing sent over both cells;

FIG. 3 is a diagram of using different scrambling codes over two cells;

FIG. 4 is a diagram of using an assistive common pilot channel (CPICH);

FIG. 5 is a diagram showing an operation mode of different redundantversions (RVs);

FIG. 6 is a diagram showing an operation mode of using a split transportblock;

FIG. 7 is a diagram showing an operation mode of using differenttransport blocks;

FIG. 8 is a diagram showing a high speed shared control channel(HS-SCCH) coding carrying a secondary cell indication bit;

FIG. 9 is a block diagram showing one slot secondary cell indicationchannel (SCICH) timing;

FIG. 10 is a block diagram showing three slots SCICH timing;

FIG. 11 is a diagram showing soft combining operations;

FIG. 12 is a diagram showing an example HS-SCCH type 1 carryingdata-to-pilot information;

FIG. 13 is a diagram showing an example of aligning the discontinuousreception (DRX) reception patterns;

FIG. 14 is a diagram showing a notification-based DRXactivation/deactivation procedure;

FIG. 15 is a diagram showing a DRX activation/deactivation procedurewith a timer;

FIG. 16 is a diagram showing a handshake-based DRXactivation/deactivation procedure; and

FIG. 17 is a diagram showing an RNC-controlled DRXactivation/deactivation procedure.

DETAILED DESCRIPTION

For optimum operations, changes may be required in a conventional WTRUreceiver and additional knowledge regarding the transmission on the WTRUside may be needed. More specifically, for the case of soft combining,the WTRU may be able to properly estimate the effective propagationchannel of the data to ensure optimum detection. This requires knowledgeat the WTRU side of the relative power between the pilot channel and thedata channel from each Node B.

In soft combining operations, the Node B scheduler may decide to nottransmit during certain TTIs (e.g., based on a channel quality indicator(CQI)) to optimize system performance. In such cases, the WTRU receivermay be reconfigured or informed such that proper reception isguaranteed.

Mechanisms for multipoint HSDPA operations with fast assistiveinformation from the Node B are described. When referred to hereafter,the term “multipoint HSDPA” may refer to multipoint operation in thesame frequency or in different frequencies. To simplify the description,many of the methods are described in the context of two sources, but itshould be understood that these concepts may be readily extended tomultiple sources. While some embodiments are described in the context ofdual cell multipoint HSDPA operation, these embodiments are equallyapplicable to multi-cell multipoint operation for downlink operation(HSDPA) or uplink operation (high-speed uplink packet access, HSUPA).Additionally, some of these embodiments may also be applicable tomultipoint Long-Term Evolution (LTE) operation, wherein the HS-DPSCH maybe equivalent to the physical downlink shared channel (PDSCH) and thehigh-speed shared control channel (HS-SCCH) may be equivalent to thephysical downlink control channel (PDCCH).

The following terminology is used herein:

“Serving high-speed downlink shared channel (HS-DSCH) cell,” “primarycell,” and “serving cell” are equivalent terms relating to the mainHS-DSCH cell. The main HS-DSCH cell is determined by the network, andtypically carries other control channels for that WTRU, such as anenhanced dedicated channel absolute grant channel (E-AGCH).

“Secondary serving HS-DSCH cell” and “secondary cell” are equivalentterms relating to at least one other HS-DSCH cell which also transmitsdata to the WTRU. The secondary serving HS-DSCH cell is assumed totransmit over the same frequency or a different frequency as the servingHS-DSCH cell. A secondary cell also may be referred to as a multipointcell or a multipoint secondary cell.

A “serving HS-DSCH cell set” is the set of all HS-DSCH cells (includingthe serving cell and any secondary serving cells) which may transmitdata to the WTRU, or equivalently for which the WTRU is configured tolisten to for HS-DSCH reception. A serving HS-DSCH cell set also may bereferred to a multipoint set.

A “primary HS-DSCH transmission” is a HS-DSCH transmission from theprimary cell.

A “secondary HS-DSCH transmission” is a HS-DSCH transmission from asecondary serving HS-DSCH cell, and may or may not carry the same dataas its associated primary HS-DSCH transmission.

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a HomeNode B, a Home eNode B, a site controller, an access point (AP), awireless router, and the like. While the base stations 114 a, 114 b areeach depicted as a single element, it will be appreciated that the basestations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 106, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 106 and/or the removable memory 132.The non-removable memory 106 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ aUTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102 cover the air interface 116. The RAN 104 may also be in communicationwith the core network 106. As shown in FIG. 1C, the RAN 104 may includeNode-Bs 140 a, 140 b, 140 c, which may each include one or moretransceivers for communicating with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The Node-Bs 140 a, 140 b, 140 c may each beassociated with a particular cell (not shown) within the RAN 104. TheRAN 104 may also include RNCs 142 a, 142 b. It will be appreciated thatthe RAN 104 may include any number of Node-Bs and RNCs while remainingconsistent with an embodiment.

As shown in FIG. 1C, the Node-Bs 140 a, 140 b may be in communicationwith the RNC 142 a. Additionally, the Node-B 140 c may be incommunication with the RNC142 b. The Node-Bs 140 a, 140 b, 140 c maycommunicate with the respective RNCs 142 a, 142 b via an Iub interface.The RNCs 142 a, 142 b may be in communication with one another via anIur interface. Each of the RNCs 142 a, 142 b may be configured tocontrol the respective Node-Bs 140 a, 140 b, 140 c to which it isconnected. In addition, each of the RNCs 142 a, 142 b may be configuredto carry out or support other functionality, such as outer loop powercontrol, load control, admission control, packet scheduling, handovercontrol, macrodiversity, security functions, data encryption, and thelike.

The core network 106 shown in FIG. 1C may include a media gateway (MGW)144, a mobile switching center (MSC) 146, a serving GPRS support node(SGSN) 148, and/or a gateway GPRS support node (GGSN) 150. While each ofthe foregoing elements are depicted as part of the core network 106, itwill be appreciated that any one of these elements may be owned and/oroperated by an entity other than the core network operator.

The RNC 142 a in the RAN 104 may be connected to the MSC 146 in the corenetwork 106 via an IuCS interface. The MSC 146 may be connected to theMGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices.

The RNC 142 a in the RAN 104 may also be connected to the SGSN 148 inthe core network 106 via an IuPS interface. The SGSN 148 may beconnected to the GGSN 150. The SGSN 148 and the GGSN 150 may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between and the WTRUs102 a, 102 b, 102 c and IP-enabled devices.

As noted above, the core network 106 may also be connected to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

Methods to schedule and receive transmissions over more than one HS-DSCHcell in one or more frequencies are described below. When multi-cellHS-DSCH reception is enabled, configured, and/or activated, the networkneeds to be able to address the WTRU and schedule the transmissions overthe HS-DSCH cells. Methods to perform data transmissions belonging toone transport block over multiple cells include sending an identicalsignal over both cells, using a common coding block but differentsignals sent over two cells, splitting the transport block over twocells, and receiving and scheduling multipoint transmissions.

In sending an identical signal over all cells, the networks send thesame data transport block to the WTRU over both the primary serving celland the secondary serving cell (for example, as in dual cell operation).As illustrated in the overlapped area in FIG. 2, identical processingover HS-PDSCH data, such as channel coding, rate matching, redundantversion (RV) selection, spreading, and scrambling, are conducted in allcells. As a result, identical signal waveforms (S) are transmitted atthe antennas of each cell. These signals are combined in the air viadifferent propagation paths. Because there is only one CRC attached tothe transport block and both cells share the same RV for this mode ofoperation, the HARQ process may be maintained as if only one cell istransmitting.

In FIG. 2, a primary serving cell 202 and a secondary serving cell 204both receive a HS-PDSCH data transport block 206. Both cells 202 and 204have the same set of processing functions (208) to generate signals S210 for transmission to a WTRU 212.

In one method of scheduling the downlink HS-PDSCH transmission toaddress the WTRU for this operation mode, the network may use oneHS-SCCH to schedule data transmissions over both cells, because thesignal over both cells is the same. Alternatively, all cells transmitthe same HS-SCCH signal using the same scrambling code to achievecross-site diversity. Alternatively, different scrambling codes may beused for transmitting the HS-SCCH over both cells.

It may be desirable for the WTRU to be aware of the assistivetransmission at a specific subframe, so that its receiver may beadjusted for optimizing the data reception. For instance, the WTRU maystart performing channel estimation on the data path over the secondaryserving cell and maximize the gain on its advanced receiver. The WTRUmay be dynamically notified of the assistive transmission via theHS-SCCH control channel or other L1 channels.

In this operation mode, the WTRU may be further configured with MIMO orbeamforming (BF). But the precoding weights used by the two cells may bedifferent for an optimal design, due to propagation path differences. Assuch, two sets of precoding weight information (PWI) bits may bereported to the WTRU via the HS-SCCH. The HS-SCCH design required tosupport the operation mode of sending identical signals from two cellsmay be modified to include an indication of the assistive transmissionon per TTI basis and/or a PWI report for the secondary serving cell.

As a small variation of this operation mode, the scrambling codes at thetwo cells may be different, as illustrated in FIG. 3. By using twodifferent scrambling codes, two different signals (S1, S2) aregenerated. The WTRU may perform demodulation according to the associatedscrambling codes and soft combining at any later processing stagewhenever two signals are deemed similar.

In FIG. 3, a primary serving cell 302 and a secondary serving cell 304both receive a HS-PDSCH data transport block 306. Both cells 302 and 304similarly perform CRC attachment, channel coding, rate matching, HARQ RVselection, physical channel mapping, and spreading on the block (308).The primary serving cell 302 performs scrambling (310) to generatesignal S1 312 for transmission to the WTRU 314. Similarly, the secondaryserving cell 304 performs a different scrambling (320) to generatesignal S2 322 for transmission to the WTRU 314.

This configuration may be applicable to the case where the WTRU isequipped with at least two antennas, so the two signals from the twocells may be effectively separated by the spatial difference of the twocells. To alleviate the separation problem, precoding weights may beapplied across the transmit antenna of the two cells. In this way, theMIMO multiplexing gain may be achieved across the antennas of the twocells.

For a secondary serving cell involved in the assistive transmission, itspilot channel, denoted by CPICH, has to be transmitted with thescrambling code assigned to this cell by the network because it has toperform its primary task to serve other WTRUs who deem this cell as aprimary serving cell. As the channel estimation is normally performedbased on the CPICH, this restriction may require a WTRU receiverfunction to be modified to process dual scrambling codes, which mayresult in two disadvantages. First, the operation is not transparent tothe single transmission mode, and the WTRU has to be informed of theassistive transmission mode on per TTI basis. Second, the legacy WTRUsthat are not capable of the receiver function change may not be able toenjoy the benefit of the multiple point transmission.

As a solution, an additional CPICH may be transmitted over the secondaryserving cell using the same scrambling code as the primary cell. Theoriginal CPICH(s) are still transmitted using the assigned scramblingcode for this cell. As the spreading factor is high (256) for the CPICHand the WCDMA cellular system is designed to allow multiple coexistingscrambling codes, the interference created by adding the assistive pilotchannel should be manageable. This solution is illustrated in FIG. 4.

In FIG. 4, a primary serving cell 402 and a secondary serving cell 404both receive a HS-PDSCH data transport block 406. Both cells 402 and 404similarly process the block (408) to generate signals S 410 fortransmission to an assisted WTRU 412. The secondary serving cell 404transmits an assistive CPICH signal 420 to the assisted WTRU 412, whichis also treated as a CPICH signal 422 by another WTRU 424.

With the configuration shown in FIG. 4, the assistive transmission istransparent to all WTRUs, as the channel estimation may be effectivelyperformed for both receive paths to the two cells by the conventionalreceiver structure. The signals from the secondary serving cell may betreated as additional multiple paths.

The design of the assistive CPICH may further include one or more of thefollowing. The assistive CPICH may not be transmitted constantly, andmay be transmitted only in the subframe where an assistive HS-PDSCHtransmission is taking place. The same cross-cell precoding as for theHS-PDSCH may be applied to the assistive CPICH, to have a cross-cellbeamforming effect to mitigate its interference to other WTRUs. Thepower of the assistive CPICH relative to other physical channelstransmitted in the secondary serving cell may be dynamically variable,to maximize the MP gain and minimize the overhead.

When using a common coding block but sending different signals over twocells, the network sends the same information or the same transportblock size to the WTRU over the two HS-DSCH cells. This may be performedby both cells using the same scrambling code or by both cells usingdifferent scrambling codes. The signals transmitted over the air may notbe necessarily the same for the two cells, even though the sametransport block of data is intended to be sent to the WTRU. This isbecause the secondary serving cell may choose a different portion of theencoded data (i.e., different redundant version (RV)) or a differentmodulation to transmit. An example of using different RVs is illustratedin FIG. 5.

In FIG. 5, a primary serving cell 502 and a secondary serving cell 504both receive a HS-PDSCH data transport block 506. Both cells 502 and 504similarly perform CRC attachment, channel coding, and rate matching onthe block (508). The primary serving cell 502 performs HARQ RVselection, physical channel mapping, spreading, and scrambling (510) togenerate signal S1 512 for transmission to the WTRU 514. Similarly, thesecondary serving cell 504 may perform different HARQ RV selection,physical channel mapping, spreading, and scrambling (520) to generatesignal S2 522 for transmission to the WTRU 514.

The assistive transmission may not necessarily be transmitted in thesame subframe with the primary transmission, as long as means ofassociating the data in the two transmissions is facilitated. For thisoperation mode, the two serving cells may not be required to operate inthe same frequency. As the soft combining of the signals from the twocells may be performed at the symbol level at a later stage of receiverprocessing, the assistive transmission from the secondary serving cellmay be configured with a different frequency band.

For soft combining at the HARQ level, each cell is required to indicateits RVs selection in HS-SCCH messages on a per-subframe basis. Thenetwork scheduler may have the flexibility to schedule multipletransmissions or retransmissions with the same RVs. At the WTRU, oncedata packets with the same RV are received, it may perform simple chasecombining on one of those packets first and then combine it with theothers at the HARQ level. Alternatively, a predetermined rule definingthe relation of the two RVs is specified, and the selection of only oneof the RVs is signaled in the HS-SCCH. Upon receiving the HS-SCCH, theWTRU determines the RV of the secondary cell by applying this rule. Forexample, the RV of the secondary cell may be equivalent to the RV of theprimary cell plus an offset (e.g., +1) in a predefined table.

As shown in FIG. 6, splitting the transport block over two cells allowsthe data to be split after the CRC is attached to the transport block. Aprimary serving cell 602 and a secondary serving cell 604 both receive aHS-PDSCH data transport block 606. Both cells 602 and 604 similarlyperform CRC attachment on the block (608). The primary serving cell 602performs channel coding, rate matching, HARQ RV selection, physicalchannel mapping, spreading, and scrambling (610) to generate signal S1612 for transmission to the WTRU 614. Similarly, the secondary servingcell 604 performs channel coding, rate matching, HARQ RV selection,physical channel mapping, spreading, and scrambling (620) to generatesignal S2 622 for transmission to the WTRU 614. The transmit processingfunctions (channel coding, rate matching, HARQ RV selection, physicalchannel mapping, spreading, and scrambling) on the two cells 602, 604may be made independently, which means that the coding rates,modulation, scrambling, etc., may be different or the same across thecells.

The transport block may be split proportionally according to the CQIsreported from the WTRU related to the propagation paths for both cells.In one example implementation, let TB1 be the preferred transport blocksize indicated by the CQI and other scheduling decisions for the primaryserving cell, and TB2 be the preferred TB size for the secondary servingcell. The total transport block size then is determined by TB=TB1+TB2.The data of size equal to TB1 will be processed by the primary servingcell and transmitted to the WTRU. The rest of the data is left to thesecondary serving cell for transmission. Alternatively, an equalsplitting scheme may be adopted that allows the two cells to transmitequal amounts of data or a predetermined rule may be used to determinehow to split the data.

In an alternate method, the data may be split into different layersacross transmission points after modulation has been performed. Morespecifically, the modulated signal may be split according to apredetermined rule across the transmission points.

How the data is to be split may be explicitly indicated to the WTRU viaHS-SCCH signaling. More specifically, separate transport block sizes ora separate number of bits to indicate the size may be signaled to theWTRU. The WTRU then decodes the HS-DPSCH accordingly. Alternatively, theWTRU receives all the information from one HS-SCCH (e.g., the primary)and uses a predetermined rule to determine the number of bitstransmitted over each cell. The WTRU may be configured semi-staticallywith this transmission scheme or dynamically, wherein it is explicitlyindicated whether the TB has been split or not according to any of thepre-determined rules. Upon receiving this indication, the WTRU mayindependently decode the data from each point or cell and combine thedata.

As only one CRC is attached to the joint transport block, the WTRU mayacknowledge the entire transport block as a whole. Therefore, only oneHARQ function is needed, even though two cells are involved in thetransmission. Once the NACK is sent to the network, both cells resendthe data simultaneously in the HARQ retransmission.

To signal the split transmission from the two cells, the existingHS-SCCH message may be reused simultaneously on each cell. Thedifference is that the transport block size indicated in the message isthe data block size after the splitting, rather than for the wholetransport block. The same or different scrambling codes may be used forthe transmission of data this way, and different weights may be appliedto each cell transmission.

Methods to perform reception and scheduling of multipoint transmissionsare described below. The transmission mode or reception mode may besemi-statically configured in the WTRU via RRC signaling or,alternatively, a more dynamic transmission mode may be performed. Thismay allow the WTRU to receive data according to any of several differenttransmission schemes over multiple points.

In one method to schedule the WTRU, the network may use one HS-SCCH toschedule the data transmissions over both cells. This HS-SCCH may betransmitted on the serving HS-DSCH cell or on a secondary cell. For thissolution, the WTRU only monitors the HS-SCCH code set of the primaryHS-DSCH cell. When the WTRU detects a HS-SCCH dedicated for that WTRUand is aware that data is scheduled over both cells, according to any ofthe solutions described herein, the WTRU may start receiving theHS-PDSCH(s) on both cells according to the information received in theHS-SCCH. Alternatively, even though only one HS-SCCH is used to indicatetransmission over two cells, this HS-SCCH may be sent over the primaryHS-SCCH or the secondary HS-SCCH.

Depending on the multipoint transmission scheme, the HS-SCCH type may bemodified to include additional information to allow the WTRU tosuccessfully decode the data. More specifically, a new HS-SCCH designmay be introduced to signal the additional information required to fullydecode the data on the secondary serving cell. This new HS-SCCH designmay require a change of the rate matching algorithm for HS-SCCH. TheWTRU may be configured to decode this type of HS-SCCH based on asemi-static configuration.

Alternatively, even though only one HS-SCCH is used to schedule theWTRU, the same HS-SCCH may be sent across all transmission points (e.g.,identical in signal wave form) to achieve cross-site diversity forenhancing the reliability of the HS-SCCH transmission at the cell edge.Alternatively, the same HS-SCCH may be repeated over all transmissionpoints, but a different scrambling code used for each HS-SCCH.

In a second method, two HS-SCCHs are used to schedule a transmissionover two cells. Depending on the transmission scheme, the HS-SCCH maycontain the same information and the WTRU knows that an assistivetransmission is taking place over both cells and performs combining atthe physical layer. Alternatively, the HS-SCCH may contain a subset ofsimilar information and a subset of different information. Morespecifically, the HS-SCCH of each cell may contain the necessaryinformation required to decode data individually on each cell, so ifcertain information, such as but not limited to, PWI, RV, modulation,etc. are different, then some of the signaled information may bedifferent. But the same HS-SCCH type (e.g., Type 3 or Type 1) issignaled over both cells.

In a third method, the HS-PDSCH sent over the two cells may notnecessarily contain the same information. More specifically, even thoughthe same transport block is being transmitted, the network may use, forinstance, a different RV or a different modulation format for the datatransmitted over the two cells, or different precoding weightinformation, possibly with the same or different scrambling codes. TheWTRU may then independently decode the two streams of data and performsoft combining at the HARQ level or at the physical layer. To providethis information to the WTRU, the same type of HS-SCCH is used to signalthe information required to receive the HS-DPSCH on each cell.

Alternatively, one HS-SCCH may be used to schedule the transmission ofthis type of data over both cells and the HS-SCCH may be sent over theprimary cell. This may require a new HS-SCCH type, wherein newinformation fields are added to the information bits required for singlecell transmission. This may include the information that may bedifferent in the secondary cell. For example, if the RV is allowed to bedifferent, the HS-SCCH may include the RV field of the secondary cell.Similarly, if a different modulation scheme is used, a secondary cellmodulation information field may be added to the HS-SCCH.

In another alternative, two different HS-SCCH types may be sent over theprimary HS-DSCH cell and the secondary HS-DSCH cell. The HS-SCCHcarrying the general information required to decode the HS-DPSCH is sentover the primary cell. This may include the information that is commonto the HS-DPSCH transmission on both cells, and the set of informationthat may be unique on the primary cell. The set of common HS-DPSCHinformation may include, but is not limited to: transport block size,HARQ process information, channelization code set, and modulation scheme(if it is not allowed to be changed). The information that may be uniqueto the transmission of the data on the primary HS-DSCH cell may include,but is not limited to: WTRU identity, RV, modulation scheme, and PWI.

It is understood that the above information is used as an example andshows a list of information from HS-SCCH type 1; however, it is alsoapplicable to cases where MIMO is used, e.g., with HS-SCCH type 3. Morespecifically, an existing HS-SCCH type may be used to signal thisinformation to the WTRU over the primary cell and a new HS-SCCH type maybe transmitted over the multipoint cells.

The HS-SCCH on the secondary cell may provide the set of informationthat differentiates the coding of the two transmissions on the primaryHS-DSCH and the secondary HS-DSCH. More specifically, it may includeonly a subset of the information needed to decode the data on theHS-DPSCH. The additional information required to decode the data in thesecondary cell for any of the methods described above (e.g., one HS-SCCHtype transmitted over both cells or two HS-SCCH types transmitted overdifferent cells), may refer to at least one or a combination of thefollowing: the RV used in the secondary cell; the modulation scheme usedin the secondary cell; the WTRU identity used in the secondary cell; thepre-coding weight information, including two additional bits that may beadded for the secondary serving cell PWI; the channelization code set,e.g., if the network schedules the WTRU over different HS-DPSCH codesthan the primary HS-DPSCH; or the power offset.

For example, if the network is allowed to use a different RV, it may usethe secondary HS-SCCH to signal the different RV that the data on thesecondary HS-DSCH is using. The WTRU identity in the secondary cell,e.g., the HS-DSCH radio network temporary identifier (H-RNTI), may bethe same as the one used in the primary cell or a different identity maybe assigned to the WTRU. In the case where only one HS-SCCH is used,then a WTRU identity for the secondary cell is not required asadditional information.

If the assistive transmission is allowed to be transmitted at adifferent subframe from the data transmission from the primary servingcell, the additional information may include an offset to the subframewhere the associated data from the primary serving cell was sent.Alternatively, this may be signaled by providing the associated HARQprocess ID in which the data from the primary cell was transmitted. Morespecifically, for this scheme the new HS-SCCH type sent over thesecondary cell may contain a HARQ process ID.

To signal this information, a new HS-SCCH type may be used for thesecondary HS-DSCH cell that only contains this subset of theinformation. The WTRU may use the general information of the primaryHS-SCCH to determine the other parameters required to decode theHS-DPSCH.

Transmission methods for different data blocks over multiple cells aredescribed below. In another operation mode, the network may senddifferent data over both cells, but the data is not transmittedsimultaneously. The two cells may or may not be operating in the samefrequency for this mode. The WTRU may be scheduled over the primaryHS-DSCH cell, with an indication over which cell the HS-DPSCH data isbeing transmitted. This scheduling may be performed dynamically on aper-TTI basis. One or a combination of the following methods may be usedto signal the cell which the network uses to transmit HS-DPSCH: modifythe HS-SCCH to include the cell ID, configure the WTRU with two H-RNTIs,the HS-SCCH code used, or the HARQ process used.

The HS-SCCH may be modified to include a cell ID, which indicates thecell over which the corresponding HS-DPSCH is being transmitted. Forexample, if the bit is set to zero, the transmission is over the primarycell; otherwise, it is transmitted over the secondary cell.Alternatively, if more than one secondary HS-DSCH cell is configured inthe same frequency, more bits may be added to the HS-SCCH to provide thecell number.

The WTRU may be configured with two H-RNTIs, e.g., a primary and asecondary. The network uses the primary H-RNTI for all primary HS-DPSCHtransmissions and the secondary H-RNTI for all secondary HS-DPSCHtransmissions.

When identifying the HARQ process used, for example, a subset of HARQprocesses is used only for transmissions on the primary cell and anothersubset is used for transmissions on the secondary cell.

The WTRU is provided with the HS-SCCH code set information to monitor onthe primary cell and the secondary cell; however, it only monitors oneHS-SCCH set at a given time. More specifically, the network maysemi-dynamically indicate to the WTRU to switch the cell it monitors viaLayer 1 or Layer 2 signaling.

In one implementation, a new Layer 1 message may order the WTRU tochange the HS-DSCH cell it is currently monitoring. The Layer 1 messagemay correspond to a new HS-SCCH order. This may be performed byintroducing a new order type, for example: Order type x_(odt,1),x_(odt,2), x_(odt,3)=‘010’. The order bits may then be set such thatthey indicate the HS-DSCH cell that may be active or that the WTRU maystart monitoring, for example:

Reserved: x_(ord,1), x_(ord,2)=x_(res,1), x_(res,2)

HS-DSCH cell to monitor x_(ord,3)=x_(hs-dsch,1)

If x_(hs-dseh,1)=‘0,’ the WTRU monitors the HS-SCCH of the primary cell.If x_(hs-dsch,1)=‘1’; the WTRU monitors the HS-SCCH of the secondarycell. The other order bits may be reserved for future use, or for use ofother secondary cells. For example, if more than two HS-DSCH cells in asingle frequency are configured, the x_(ord,2) bit may be used in asimilar way as x_(ord,3).

Alternatively, an existing order may be used, such as the order used forDC-HSDPA. More specifically, the bit used to activate or deactivate asecondary cell in a different frequency may be used to indicate to theWTRU to switch HS-DSCH cells. More specifically, if the order indicatesto activate the secondary cell (and if configured with multipointoperation), the WTRU switches HS-SCCH reception to the secondary cell onthe same frequency. When the order is given to deactivate the secondarycell, the WTRU falls back to perform HS-SCCH reception on the primaryHS-DSCH cell. When the WTRU receives the order, it may retune itsreceiver to the indicated cell and start monitoring the HS-SCCH of thatnew cell X TTIs upon receiving the order, where X is a predefined value.

In a second implementation, a medium access control (MAC) controlprotocol data unit (PDU) may be used to indicate to the WTRU the HS-DSCHcell it should be monitoring, e.g., a cell number. The MAC control PDUmay indicate an activation time and the WTRU may start monitoring thenew cell upon successful reception of the packet or X TTIs aftersuccessful reception of the packet.

Alternatively, the WTRU is configured to monitor the HS-SCCH of bothcells simultaneously, but may only receive HS-DPSCH data over one cellat a time. In particular, the same H-RNTI that specifies the WTRU ID isapplied to the HS-SCCH messages from both cells. If the WTRU receives aHS-SCCH that is addressed to it from one of the cells, it starts todemodulate the corresponding HS-PDSCH data from this cell.

In an alternate mode of HS-DSCH operation in a single frequency,different transport blocks may be sent over the two HS-DSCH cells,potentially simultaneously over both cells, which may be or may not beoperating in the same frequency. In FIG. 7, a primary serving cell 702receives a first HS-PDSCH data transport block 704. The primary servingcell 702 processes the block (706) to generate a signal S1 708 fortransmission to a WTRU 710. A secondary serving cell 720 receives asecond HS-PDSCH data transport block 722. The secondary serving cell 720processes the block (724) to generate a signal S2 726 for transmissionto the WTRU 710.

The WTRU may be addressed by using two independent HS-SCCHs over twocells. More specifically, the WTRU may be configured to monitor anHS-SCCH code set for each activated cell. If the WTRU detects its H-RNTIover any of the cells, it decodes the corresponding HS-PDSCH on thatcell. With this way of addressing the WRTU, it may be possible todynamically alternate to the switching-based operation mode describedabove. If only one HS-SCCH message is received from one of the cells, itonly decodes the HS-PDSCH from that cell. The other cell may beconsidered as not transmitting.

In an alternate method, to avoid the WTRU monitoring the HS-SCCH(s) fromboth cells, cross-cell scheduling may be used. In one example ofcross-cell scheduling, one HS-SCCH may carry the information for bothcells, e.g., all the information required for both HS-DSCH cells istransmitted on one HS-SCCH, which may be scheduled on the primaryHS-DSCH cell. This may be by a new HS-SCCH type (e.g., type 4) or byexisting HS-SCCH type 3.

Dynamic scheduling among different transmission modes is describedbelow. As described above, the WTRU may operate with a variety oftransmission modes in a multipoint operation. In practical deployment,some of the operation modes may be advantageous in some channelconditions, while other operation modes may be better in otherscenarios. For example, at a low SNR condition, the joint transmissionof the same information from both cells may offer the best gain. Whileat a high SNR, simultaneous transmission of different information oneach cell to the same WTRU may be more beneficial. A HS-SCCH design thatallows a dynamic and seamless switching among various operation modesmay permit maximizing the performance gain provided by the multiple celltransmission.

When the assistive transmission is taking place at a specific subframe,most likely all the data resources of the secondary serving cell wouldbe made available to the assistive transmission using the either thesame scrambling code or a different scrambling code as the primary cell.Otherwise, sending data simultaneously to other WTRUs via differentchannelization codes would generate unnecessary interference and degradethe benefit of the assistive transmission.

Under this assumption, the channel codes used for the HS-PDSCH in boththe primary cell and the secondary cell may be the same, or different ina pre-defined manner. Thus, the field indicating the channelizationcodes used for data transmission in the HS-SCCH transmitted from one ofthe cells may be made available for the desired signaling purposes.

In one solution of allowing dynamic switching among different operationmodes, two HS-SCCHs are transmitted with different scrambling codesassociated with each cell originally configured by RRC, so that they maybe demodulated correctly at the WTRU. To use the same scrambling codesfor the HS-SCCHs for both cells, the WTRU has to be equipped with atleast two antennas to rely on sufficient spatial diversity todistinguish the two HS-SCCHs at the WTRU. Both HS-SCCHs may be addressedto the same WTRU by applying the same or different H-RNTI. If the WTRUdetects an HS-SCCH addressed to the WTRU from the secondary HS-DSCHcell, the WTRU then determines that a multipoint transmission is takingplace and starts receiving the corresponding HS-PDSCH on both HS-DSCHcells.

In a first method, the network may determine dynamically, withoutreconfiguration, one of the operation modes for data transmission. Toinform the WTRU about the operation mode, the full channelizationindication field in the HS-SCCH sent by the secondary serving cell maybe re-used to indicate the operation mode. More specifically, thechannelization code set information bits, denoted by x_(ccs,1),x_(ccs,2), . . . , x_(ccs,7), in the secondary HS-SCCH may be re-definedfor signaling different operation modes. An example is given in Table 1,which uses two bits in the field.

TABLE 1 Example of signaling the operation modes x_(ccs,1) x_(ccs,2)Mode of operation 0 0 Simultaneous transmission of same signal over bothcells 0 1 Simultaneous transmission of the same transport block overboth cells, but with different RVs 1 0 Transmission of differenttransport blocks over both cells 1 1 Reserved

Other fields in the secondary HS-SCCH may be maintained with the sameusage. For example, transport block size information may still be usedfor its original purpose to indicate the transport block size for thesecondary HS-PDSCH.

If the assistive transmission is transmitted at a different subframefrom the primary data transmission, the additional bits in the field maybe used as shown in Table 2, for example, to indicate an offset to thesubframe where the data from the primary serving cell is sent, or a HARQprocess ID may be specified.

TABLE 2 Example of signaling the subframe offset x_(ccs,6) x_(ccs,7)Subframe 0 0 Assistive transmission takes place in the same subframe asthe primary transmission 0 1 Assistive transmission takes place onesubframe after the primary transmission 1 0 Assistive transmission takesplace two subframes after the primary transmission 1 1 Assistivetransmission takes place three subframes after the primary transmission

Switching the operation modes may be made on a per-TTI basis, as theoperation mode may be updated every TTI as long as the HS-SCCH istransmitted.

In a second method, the channelization code set information bits arepartially used for signaling the multipoint transmission. The networkstill may indicate different channelization codes for the assistivetransmission. Let 0 represent the starting code and P the number ofcodes used for the data transmission; only 0 may be required to be thesame for both cells. The secondary serving cell may indicate a differentnumber of channelization codes used for the assistive data transmission.Therefore, different transport block sizes may be scheduled over thesecondary serving cell. In particular, the bits from the channelizationcode set information field may be used as follows for the secondaryserving cell.

For the first three bits (code group indicator) of which x_(ccs,1) isthe most significant bit (MSB):

x _(ccs1) ,x _(ccs,2) ,x _(ccs,3)=min(P−1,15−P)

then the fourth bit is defined by

x _(ccs4) =└P/8┘

Optionally, for the first four bits (code group indicator) of whichx_(ccs,1) is the MSB:

x _(ccs,1) ,x _(ccs,2) ,x _(ccs,3) ,x _(ccs,4) =P−1

The rest of the bits in the channelization code set information fieldmay be used to signal the operation mode, or optionally, the subframeoffset if the assistive data is transmitted in a different subframe asthe primary cell. An example of such use is illustrated in Table 3 inconjunction with Table 2, where one bit is used to indicate theoperation modes and two bits are used to signal the subframe offset.

TABLE 3 Example of signaling the subframe offset of second methodx_(ccs,5) Mode of operation 0 Simultaneous transmission of transportblocks over both cells 1 Transmission of different transport blocks overboth cells

In the operation mode indicated by x_(ccs,5)=0, different RVs may stillbe used in the assistive transmission for the secondary serving cell,which may be signaled in the redundancy and constellation version fieldcarrier on the HS-SCCH from the secondary serving cell.

The operation mode to be used on a particular subframe for the assistivetransmission may be left to network to decide. Triggering criteria forswitching may be applied individually or in any combination of thefollowing: based on the range of CQIs reported by the WTRU; based on thepath loss reported by the WTRU; based on the handover status ormeasurements reported by the WTRU; or based on the scheduling loads ofboth primary and secondary serving cells.

Methods to inform the WTRU of the presence of secondary transmissionsare described below. To maximize the use of the network resources, thenetwork may use soft combining operations only when judged necessary(e.g., based on CQI feedback from WTRUs). The following methods may beused individually or in any combination. In addition, these methods alsomay be used to activate or deactivate dual cell in single frequencyoperation even for schemes that do not require soft combining.

Fast activation/deactivation mechanisms may be used, in which the WTRUis informed on a semi-static basis of the presence of secondarytransmissions. This may be achieved, for example, via theactivation/deactivation mechanisms offered by the HS-SCCH orders. Thesetransmissions may or may not carry the same data.

In a first method, the WTRU is configured to receive secondarytransmissions, or equivalently the secondary cell is said to be enabled.This configuration is carried out using L3 configuration messages, e.g.,via RRC signaling. The Node B may then deactivate and re-activate thesecondary cell using the existing or new HS-SCCH orders.

To support the activation and deactivation of secondary serving HS-DSCHcells from other Node Bs than the serving HS-DSCH cell, additional rulesfor activation/deactivation via HS-SCCH orders may be required. To allowmore flexibility at each Node B scheduler, each Node B may decide theactivation/deactivation status for the secondary cells it controls. Toallow such control, the WTRU may deactivate a secondary serving HS-DSCHcell only when it receives the deactivation order from that cell, or theWTRU may activate a secondary serving HS-DSCH cell only when it receivesthe activation order from that cell.

Alternatively, a centralized control may be desired for a networkimplementation. In such cases, the WTRU may deactivate a secondaryserving HS-DSCH cell only when it receives the deactivation order fromthe primary cell, or the WTRU may activate a secondary serving HS-DSCHcell only when it receives the activation order from the primary cell.

Alternatively, the order to activate or deactivate may be received fromany of the HS-DSCH cells where the WTRU is continuously monitoring theHS-SCCH code set.

Alternatively, the activation order for a secondary HS-DSCH cell on thesame frequency may only be sent by the Node B or received by the WTRUfrom a HS-DSCH cell on that same frequency.

In the context of multi-frequency and multipoint downlink operations,the WTRU may be configured with two cells, for example, on adjacentfrequencies or on different bands or frequencies. Each of those cellsmay have associated secondary (multipoint) cells on that frequency. Aprimary frequency and a secondary frequency are defined, and there isone serving HS-DSCH cell per frequency.

The “primary frequency serving HS-DSCH cell” (also referred to as the“primary cell”) is the primary cell on the primary frequency. The“secondary frequency serving HS-DSCH cell” (also referred to as the“secondary frequency primary cell”) is the primary cell on the secondaryfrequency and may correspond to the same Node B or sector as the primaryfrequency serving HS-DSCH cell. The “primary frequency secondary servingHS-DSCH cell” (also referred to as the “primary frequency secondarycell”) is the secondary cell associated to the primary frequency. The“secondary frequency secondary serving HS-DSCH cell” (also referred toas the “secondary frequency secondary serving cell”) is the secondarycell associated to the secondary frequency.

It is understood that if multipoint transmissions are possible overdifferent frequencies, then a secondary serving cell may correspond tothe multipoint cell in the second frequency (e.g., the non-primaryfrequency). In such configurations, additional restrictions on theactivation and deactivation mechanisms may be implemented. For example,when the secondary frequency serving HS-DSCH cell is deactivated, thesecondary frequency secondary serving HS-DSCH cell is also deactivated.

When a dual cell dual carrier and dual cell single frequencyconfiguration is activated, the WTRU and the network may use theexisting HS-SCCH orders used for 4C-HSDPA to control the activation ordeactivation of the secondary HS-DSCH cells. This may be achieved byproviding a mapping or an order for the cells to activate or deactivate.The order of the cells to activate or deactivate may follow a predefinedrule or a configuration order. For example, the numbering may start withthe primary frequency secondary HS-DSCH cell. In this example, thenumbering may be as follows: the first secondary HS-DSCH cell is thesecondary cell (or multipoint cell) on the primary frequency, the secondsecondary HS-DSCH cell is the secondary frequency serving HS-DSCH cell(if configured), and the third secondary HS-DSCH cell is the secondaryfrequency secondary serving HS-DSCH cell (if configured).

In another example, the numbering may start with the secondary frequencyserving HS-DSCH cell, such as: the first secondary HS-DSCH cell is thesecondary frequency serving HS-DSCH cell (if configured), the secondsecondary HS-DSCH cell is the primary frequency secondary servingHS-DSCH cell (if configured), and the third secondary HS-DSCH cell isthe secondary frequency secondary serving HS-DSCH cell (if configured).In both of these examples, it is understood that if one of the cells isnot configured, the numbering may change according to the order of theconfigurations that are present.

When the secondary cell is located in a different Node B than theprimary cell, an additional delay due to the Iub/Iur interface overheadmay be required for activation and deactivation. In such cases, adifferent activation/deactivation delay may be prescribed. Optionally,the WTRU may receive the activation/deactivation delay from the networkvia the higher layers (e.g., RRC signaling), and the delay foractivation and deactivation may be different. In a configuration wherethe cells are not located in the same Node B or there is nocommunication between the sectors of a Node B, when a decision toactivate or deactivate a cell is taken, the cell taking the decision maynotify the other Node B, the other cells, or the RNC.

The decision to activate or deactivate a secondary HS-DSCH cell may betaken by the primary HS-DSCH serving cell or a secondary HS-DSCH servingcell. Even though the decision may be taken by one Node B, the order toactivate or deactivate may be given by the other Node B. Additionally,once a decision to activate or deactivate is made, the RNC may also beinformed to properly direct the data to the Node Bs.

If the primary Node B takes the decision to activate or deactivate thecell in a secondary Node B, the primary HS-DSCH cell sends anactivation/deactivation order to the WTRU to activate or deactivate thecorresponding secondary HS-DSCH serving cell. The Node B then informsthe other Node B and/or RNC (serving and/or controlling) via Iub/Iursignaling of the HS-DSCH serving cells that have been activated ordeactivated. Alternatively, the Node B only informs the secondaryHS-DSCH serving cell and/or the RNC of the activation/deactivation whenan acknowledgement (ACK) to the order is received.

Alternatively, the primary HS-DSCH cell first notifies the other Node Band/or RNC of the decision to activate or deactivate the secondaryHS-DSCH cell using Iub/Iur signaling. To ensure proper synchronizationbetween the Node Bs and the WTRU, the serving Node B may optionallyindicate a time stamp or activation time of the time that the servingprimary cell is expecting or wants the secondary HS-DSCH cell to beactivated or deactivated. At the activation time, the primary HS-DSCHcell or the secondary HS-DSCH cell (dependent on which cell can send theorder) sends the activation/deactivation order to the WTRU.

Alternatively, the primary HS-DSCH cell notifies the other Node B and/orthe RNC of the decision. The actual order or signaling to activate ordeactivate the corresponding HS-DSCH cell is sent only if the other NodeB approves the decision. The approval may be sent to the primary celland/or the RNC via Iub/Iur signaling. The approval may be in the form ofa single bit, indicating yes or no, or alternatively the approval mayprovide an activation time to the primary cell and/or the RNC indicatingthe time at which it will allow activation (or deactivation) of thesecondary HS-DSCH cell. If approved, at the given activation time, theprimary carrier and/or the secondary carrier may signal to the WTRU toactivate or deactivate the cell. The activation time may correspond to apredefined time after the transmission of these messages, to theactivation time initially signaled by the primary carrier, or to theactivation time signaled to the primary carrier by the secondarycarrier.

Similarly, if the secondary cell takes a decision to activate ordeactivate itself, it may send an order to the WTRU and then notify theprimary Node B and/or the RNC, or only notify the primary Node B and/orthe RNC when an ACK is received. Alternatively, the secondary cell maynotify the primary cell and other secondary cell(s) and/or the RNC, ifapplicable, and proceed using similar actions to the ones described forthe primary HS-DSCH cell taking the decisions.

If the decision is to activate the secondary HS-DSCH cell and the WTRUis not receiving HS-DSCH data from the secondary cell, the secondaryNode B has to notify the primary Node B to send the activation order.The secondary cell may also notify the RNC and the RNC may optionallynotify the primary Node B. Similarly, the secondary cell may send anactivation time to the primary Node B and/or the RNC. At the givenactivation time, the secondary cell assumes that the cell has beenactivated by the primary cell and may start transmission in the downlink(DL) at the activation time or allow some delay, to ensure that the cellhas been properly activated. Additionally, the RNC may also assume thatthe primary Node B has successfully activated the secondary cell at thegiven activation time or at the time of the indication and start sendingdata to the secondary Node B. Alternatively, the RNC may delay sendingdata to the secondary cell to allow for proper activation time.

Alternatively, the secondary cell may only start transmission in the DLwhen it detects that a CQI report corresponding to the secondary HS-DSCHcell has been sent by the WTRU. Alternatively, the secondary cell maywait for an acknowledgment by the primary Node B that the activation hassuccessfully taken place. This is also applicable to the case where theorder is not sent from the Node B that took the decision. Alternatively,the secondary cell notifies the RNC upon determining that the secondarycell has been successfully activated. The notification may be in theform of a data request or as an explicit indication. A similar proceduremay be followed for the deactivation of a secondary cell.

Upon notification of a fast deactivation of a secondary cell, the RNCmay stop sending data to the WTRU. Optionally, for the methods describedabove, the secondary Node B may attempt to empty its buffer prior todeactivating the secondary cell. The RNC may stop sending new data tothis secondary cell during this time.

Alternatively, the RNC makes the decisions and notifies thecorresponding Node B of the decision and/or indicates to the Node B thatan activation or deactivation should be performed.

It is understood that the notifications from Node B to Node B may bedone directly, or via the RNC, where the RNC receives the notificationfirst and then relays it to the other Node B.

Notifying the other Node B may be needed because the controlling Node Bmay not be able to send the order, or because the Node Bs need to knowfor scheduling and to ensure proper detection of the HS-DPCCH. When asecondary serving HS-DSCH cell in the same frequency is activated ordeactivated, the HS-DPCCH format or coding may change. If this occurs,the serving Node B and/or other Node Bs may need to be notified of thechange, so that it may properly decode the HS-DPCCH.

Alternatively, predefined rules for deactivation exist between the NodeBs. In one implementation, the rule may depend on the reported CQIvalues. The CQI values may be received and decoded by both Node Bs. Whenthe CQI value or an average CQI of the secondary Node B has been below athreshold for a predefined period of time, then the secondary Node B isdeactivated. The primary Node B, which is also aware of the reported CQIvalues, determines that the criteria has been met and deduces that thesecondary Node B has been deactivated. If the HS-SCCH orders are onlysent over the primary HS-SCCH, then the primary Node B sends adeactivation order to the WTRU.

Additionally, when the activation takes place, the Node B may alsonotify the RNC via Iur signaling of the activation, so propertransmission of the radio link control (RLC) packets may take place overboth HS-DSCH cells. Likewise, when the deactivation takes place, theNode B notifies the RNC via Iur signaling of the deactivation, so thattransmission of the RLC packets may be interrupted over the deactivatedHS-DSCH cells.

The WTRU may be informed on a TTI by TTI basis (dynamic) whether or notit should receive data from the secondary serving cell (also referred toas an assistive transmission). In a first method, the WTRU monitors theHS-SCCH (potentially more than one channelization code) from the servingHS-DSCH cell. The HS-SCCH carries a special indication for the WTRU tocombine or decode the HS-PDSCH from a different cell. This approach mayapply to both soft combining and source multiplexing (multiflow)operations. This indication may be carried in the first part of theHS-SCCH, such that it is decoded before the associated HS-PDSCH isreceived.

In a first implementation of this method, a dedicated information bit isadded to the HS-SCCH. This concept is illustrated in FIG. 8, where anadditional bit (X_(sci)) is carried in the first part of the channel.This added bit requires changes in the rate matching block, which mayrequire puncturing three more bits than the rate matching block in theconventional HS-SCCH type 1.

In an alternative approach to adding an information bit to the existingHS-SCCH coding scheme, one of the existing fields may be re-interpretedto carry the assistive transmission information. As an example, theX_(ccs) field may be restricted, to free one information bit to carrythe X_(sci).

In a second implementation of this method, the presence of an assistivetransmission or a transmission on the secondary cell is indicated to theWTRU by the Node B via a specific choice of channelization code from theset of configured HS-SCCH channelization codes. One way to implementthis approach is to use the HS-SCCH number, that is, the configurationnumber of the HS-SCCH in the RRC configuration message (the order of theHS-SCCH in the RRC configuration message).

The HS-SCCH number information is already used when 64QAM is configured.More specifically, information is carried on the HS-SCCH mod 2 (even/oddcharacteristic). Because this HS-SCCH number may also be used when theWTRU is configured for 64QAM operations to ensure that the two featuresmay work simultaneously, all combinations of X_(sci) and even/oddHS-SCCH numbers are possible. This concept may be achieved as shown inTable 4.

TABLE 4 Example HS-SCCH and X_(sci) mapping HS-SCCH number HS-SCCHnumber mod 2 Xsci 0 0 0 1 1 0 2 0 1 3 1 1

As shown in Table 4, this particular mapping for the X_(sci) withrespect to the HS-SCCH number ensures that any combinations with HS-SCCHnumber mod 2 are possible. This particular implementation also may beextended to a larger number of HS-SCCH configured codes.

In a second method, the WTRU is configured to monitor one set ofHS-SCCHs per activated cell. When the WTRU detects an HS-SCCH from asecondary cell, it decodes the associated HS-PDSCH. When soft combiningis configured, the WTRU may be configured to not apply soft combiningwhen the HS-SCCHs from the different cells for the same TTI indicatedifferent transport block sizes or conflicting information.

In another implementation of this method, the network indicates thepresence of an assistive transmission by sending the HS-SCCH over thesecondary HS-DSCH cell; otherwise, the HS-SCCH on the primary cell isused. More specifically, the WTRU monitors a configured HS-SCCH set foreach activated HS-DSCH cell. If the WTRU detects an HS-SCCH addressed tothe WTRU from the secondary HS-DSCH cell, the WTRU then determines thatan assistive transmission is taking place and starts receiving thecorresponding HS-PDSCH on both HS-DSCH cells. If the WTRU detects anHS-SCCH addressed to the WTRU from the primary HS-DSCH cell, the WTRUdetermines that the data transmission is only taking place on theprimary HS-DSCH.

In a third implementation of this method, the network indicates thepresence of an assistive transmission by sending the HS-SCCHssimultaneously over both the primary HS-DSCH cell and the secondaryHS-DSCH cell if the assistive transmission from the secondary servingcell occurs. While HS-PDSCH data is sent using the same scrambling code,mostly the one used by the primary serving cell, the HS-SCCHs aretransmitted with different scrambling codes associated with each celloriginally configured by RRC, so that they may be demodulated correctlyat the WTRU. Both HS-SCCHs are addressed to the same WTRU by applyingthe same H-RNTI. If the WTRU detects an HS-SCCH addressed to the WTRUfrom the secondary HS-DSCH cell, the WTRU then determines that anassistive transmission is taking place and therefore starts receivingthe corresponding HS-PDSCH on both HS-DSCH cells. Other informationfields in the HS-SCCH from the secondary serving cell may be differentfrom the primary serving cell, which may be used to indicate thetransmission mode, as described above.

In a third method, the WTRU monitors a new control channel carrying theassistive information (X_(sci)). This new control channel (secondarycell indication channel, SCICH) may be built using a similar structureas the existing fractional dedicated physical channel (F-DPCH) tominimize the code space usage and at the same time re-use the existingfunctionality. To ensure appropriate timing, this SCICH may be sent inthe same slot as the associated first part of the HS-SCCH, as shown inFIG. 9, for example.

In another alternative, the SCICH carries the information over threeconsecutive slots and sends the information such that the last of thethree slots is sent during the first part of the associated HS-SCCH.This concept is illustrated in FIG. 10, and allows transmission powersavings as the WTRU may combine received energy from three slots beforemaking the appropriate decision. The delay also allows for appropriatedecoding of the HS-PDSCH. Alternatively in that case, the SCICH also maybe carried using similar coding as the E-DCH HARQ acknowledgementindicator channel (E-HICH) and E-DCH relative grant channel (E-RGCH).

In an alternate solution, the presence of an assistive transmission or atransmission on the secondary cell is indicated to the WTRU by the NodeB via a specific H-RNTI. More specifically, the WTRU may be configuredwith two H-RNTIs, a primary H-RNTI and a secondary H-RNTI. The WTRU maymonitor the configured HS-SCCH set for one of the two H-RNTIs over theprimary HS-DSCH cell. The WTRU is addressed with the primary H-RNTI whentransmissions over the primary cell only are scheduled, while thesecondary H-RNTI is used to schedule transmissions over the primary celland the secondary cell. When the WTRU detects a HS-SCCH with thesecondary H-RNTI, the WTRU determines that an assistive transmission ora transmission on a secondary cell is taking place.

In another solution, the network only uses assistive transmissions whenit determines that the first transmission or a second transmission wasnot successfully received by the WTRU or, for example, when the channelconditions perceived by the WTRU for the primary cell are notsatisfactory.

The Node B may use several criteria to determine whether to send anassistive transmission. The WTRU may then determine whether thescheduled transmission is being performed over one or more cellsaccording to one or combination of the following criteria: the new dataindicator, the RV of the transmission, the modulation format and TBsize, or the HARQ process number.

If according to the new data indicator, the current transmissioncorresponds to a retransmission, the WTRU starts receiving over bothcells.

When using the RV of the transmission, if the WTRU detects that thetransmission is performed using a special combination of the s,r,b bits,e.g., the X_(rv) value corresponds to a predetermined value, then theWTRU knows that the transmission is an assistive transmission.Alternatively, this criteria may also depend on the specific “s” value.For example, if s=1, the Node B performs assistive transmissions;otherwise it only transmits over the primary HS-DSCH cell.Alternatively, this criteria may depend on the value of the r bit, or acombination of the s and r bits.

When using the modulation and TB size, the Node Bs only performassistive transmissions for a subset of TB sizes and modulation format.If the WTRU determines that the TB size and/or modulation formatcorresponds to one of these preconfigured subsets, it performs assistivereception of data.

When using the HARQ process number, the WTRU and the Node B arepreconfigured to use assistive transmissions only when a certain HARQprocess is used. For example, if the WTRU determines that the HARQprocess ID indicated in the HS-SCCH corresponds to one suchpreconfigured HARQ process, it performs assistive reception over bothHS-DSCH cells.

The decision to perform assistive transmissions may be dependent on theCQI reported by the WTRU on both cells. For example, if the CQI value onthe serving cell is below a threshold for a configured period of timeand the CQI value of the secondary serving cell is above a threshold,the Node B may perform assistive transmissions. When this criteria ismet, the Node B starts assistive transmissions, and when it determinesthat this criteria is met, then it autonomously starts to receive as ifassistive transmissions are ongoing.

Methods to improve soft combining at the WTRU are described below. Insoft combining operations, the multiple Node Bs transmit the same datato the WTRU at the same time (with some reasonable delay requirements).In one option, the data is sent by the Node Bs using the same physicalformat, e.g., using the same spreading, scrambling, physical mapping,and encoding such that the WTRU may combine the signal at the chip orsymbol level. In another option, the data is sent by the Node Bs using adifferent physical format (different spreading codes, scrambling, andphysical channel mapping) but the same coded bits are transmitted, suchthat the WTRU may combine the data at the coded bit level (symbollevel). To correctly demodulate the data from both Node Bs, the WTRUrequires a distinct pilot signal from each Node B to perform channelestimation; this concept is illustrated in FIG. 11.

For the WTRU to perform optimal combining, at the chip level or thesymbol level, it is required to have knowledge of the channel over whichthe data is transmitted from each Node B. More specifically, the WTRUrequires knowledge of the effective channel it sees from both Node Bs.The effective channel may be interpreted as the combination of the twodata channels as perceived by the WTRU. Because the data channels may betransmitted with different relative power with respect to the pilotchannel from each Node B, the effective channel for the data signal isdifferent than the effective channel perceived for the pilot signals.With the existing mechanisms, the WTRU may only measure the effectivechannel from the pilot signals.

The performance of soft combining at the WTRU may be improved bysignaling power offset information. In this approach, the WTRU isinformed of the relative power between the data signal and the pilotsignal from one or more of the HS-DSCH cells in the serving HS-DSCH cellset for that WTRU. The WTRU uses the power offset information in itsreceiver to improve the performance via better channel estimation andimproved combining (for example, maximum ratio combining).

The network may inform the WTRU of the data-to-pilot power offset (orequivalently the pilot-to-data power offset) for the secondary servingHS-DSCH cell(s) on a dynamic, semi-static, or static basis. In oneoption, each cell in the serving HS-DSCH cell set signals the WTRU withthe data-to-pilot power offset used.

In dynamic data-to-pilot power offset signaling, the network signals thedata-to-pilot power offset to use for data demodulation on a TTI by TTIbasis. The data-to-pilot power offset may be carried on the HS-SCCHalong with the conventional information carried on the HS-SCCH for datademodulation.

In a first approach to dynamic data-to-pilot power offset signalingusing the HS-SCCH, the data-to-pilot power offset information is carriedin the first part of the HS-SCCH so that the information may be used forHS-PDSCH demodulation. In one option, a new encoding scheme for theHS-SCCH is designed to carry the new information. This encoding schemeincorporates a new set of bits carrying the data-to-pilot information(X_(d2p)) in addition to the channelization code set bits (X_(ccs)) andmodulation schemes bits (X_(ms)), a concept illustrated in FIG. 12.

In one implementation, the same number of bits is carried in X₁ so thatno modification to the conventional encoding scheme is necessary. Thismay be accomplished by reducing the allowable channelization code setand modulation scheme set for the WTRU configured in multipoint HSDPA.The bits freed from that reduction may be used for the d2p field and theconventional channel coding 1, and rate matching 1 may be re-used.

In another implementation, the same number of channelization code setand modulation scheme bits are used and X₁ also carries the additionalX_(d2p) bits. To achieve this, the rate matching may be changed topuncture less bits, leading to a higher code rate and potentiallyrequiring more power for the same reliability. For example, if X_(d2p)carries three bits of information, the new Z₁ has 57 bits, and since thenew R₁ may have 40 bits, a total of 17 bits may be punctured, as opposedto eight in the conventional HS-SCCH type 1. The choice of theadditional nine bits to puncture may be based on offline simulations,for example.

The dynamic approach potentially leads to the best performance at theexpense of additional downlink overhead. For inter-Node B operations,this approach also requires a fast backhaul link between the Node Bs inthe serving HS-DSCH cell set such that the power offset is relevant whenit is transmitted by the serving Node B cell.

Alternatively, the HS-SCCH is also transmitted from the secondaryserving HS-DSCH cell. For intra-Node B operations, there is no backhaullink requirement and the information may be carried in the HS-SCCHassociated to the serving HS-DSCH cell only. The HS-SCCH transmittedover the secondary serving HS-DSCH cell may be encoded according to thesolutions described above.

In an alternate solution, the HS-SCCH transmitted over the secondaryserving HS-DSCH cell may contain a reduced set of information. Giventhat the HS-DPSCH information sent over the cells is the same, theHS-SCCH information such as channelization code set, modulation scheme,TB size, HARQ, RV, and new data indication in addition to otherinformation, such as, but not limited to, WTRU identity, are transmittedover one of the cells, such as the primary HS-DSCH cell. The otherHS-DSCH cell transmits the data-to-pilot power ratio and optionally anyother potential information differentiating the two transmissions. Forexample, the following information may be transmitted by the new HS-SCCHover the secondary HS-DSCH cell:

Data-to-pilot power offset (y bits): x_(d2p,1), x_(d2p,2), . . .x_(d2p,y)

WTRU identity (16 bits): x_(ue,1), x_(ue,2), . . . , x_(ue,16)

where y may depend on the range and granularity of the required poweroffset.

In the semi-static signaling approach, the network signals thedata-to-pilot power offset at most at each HS-DSCH transmission instant(for which there is data transmitted on the secondary serving HS-DSCHcell). This may be achieved using a new L1 signaling mechanism. In oneexample of the L1 signaling mechanism, a new HS-SCCH order is used. Thenetwork signals the data-to-pilot power offset information in the formof an index to a predefined table of data-to-pilot power offset values.

The following information may be transmitted by means of theconventional HS-SCCH order physical channel:

Order type (3 bits): x_(odt,1), x_(odt,2), x_(odt,3)

Order (3 bits): x_(ord,1), x_(ord,2), x_(ord,3)

WTRU identity (16 bits): x_(ue,1), x_(ue,2), . . . , x_(ue,16)

In one example, a new order type is defined for the power offset HS-SCCHorder and the power offset index is carried in the three bits of theHS-SCCH order bits. For example, when order type x_(odt,1), x_(odt,2),x_(odt,3)=“101,” then the mapping for x_(ord,1), x_(ord,2), x_(ord,3)may be as shown in Table 5 and indicates the data-to-pilot power offset.

TABLE 5 HS-SCCH order mapping for data-to-pilot power offset Index todata-to-pilot power x_(ord,1) x_(ord,2) x_(ord,3) offset 0 0 0 0 0 0 1 10 1 0 2 0 1 1 3 1 0 0 4 1 0 1 5 1 1 0 6 1 1 1 7

Upon receiving the HS-SCCH order indicating the pilot-to-data poweroffset, the WTRU calculates the actual value of the pilot-to-data poweroffset by finding the data-to-pilot power offset entry in apre-configured pilot-to-data power offset reference table (e.g., asshown in Table 6) corresponding to the signaled data-to-pilot offsetindex (D2PI). Optionally, the network also configures an additionaloffset index (AOI) that the WTRU applies to the D2PI to obtain theactual pilot-to-data power offset. In such case, the actual index to thereference table becomes D2PI+AOI.

TABLE 6 Example pilot-to-data power offset reference table Pilot-to-datapower offset D2PI (dB) 0 0 1 0.5 2 1 . . . . . . 10  15

In another alternative to signaling semi-static data-to-pilot poweroffset, the network signals the data-to-pilot power offset (orequivalently an index to a table with the optional additional offsetindex as described above) via a L2 message. For example, thedata-to-pilot power offset may be carried in the header of the MAC-ehs(or the new MAC layer supporting the multipoint HSDPA functionality).This new header field may carry the index to the quantized pilot-to-datapower offset table. A new MAC control PDU may be created to signal tothe WTRU the power offset. To indicate to the WTRU that the MAC PDUcorresponds to a control PDU, a special value of the logical channelidentifier (LCH-ID) may be reserved to indicate that the payloadcorresponds to a control PDU and for this case multipoint HSDPA controlinformation. Optionally, a new field may follow the LCH-ID, indicatingwhat type of control PDU the payload corresponds to. This may bebeneficial to introduce other control PDUs.

The WTRU applies the signaled pilot-to-data power offset for receivingthe next HS-PDSCH (for example, when L1 signaling is used) oralternatively after a pre-configured time delay following reception ofthe data-to-pilot power offset value. The WTRU maintains the samepilot-to-data power offset value until it receives a new value, until aphysical channel reconfiguration is received, or until the secondaryHS-DSCH serving cell is deactivated.

In an example of static data-to-pilot power offset signaling, the WTRUis configured by the network with a data-to-pilot power offset value viaRRC signaling. The network may signal an index to a table of quantizedvalues. The WTRU applies the data-to-pilot power offset for HS-DSCHreception when appropriate (i.e., whenever it receives data from thesecondary HS-DSCH cell which it knows is destined to be soft-combined).

The WTRU maintains the data-to-pilot power offset signaled by thenetwork until a new value is configured. In one option, the WTRUreceives a data-to-pilot power offset via RRC signaling which it usesuntil it receives a new value via one of the approaches described above.

In another option, the network signals the WTRU with a measurement poweroffset F (in dB) for each cell in the serving HS-DSCH cell set. The WTRUdetermines the relative power of the data channel from each cell basedon this measurement power offset. It is assumed that the measurementpower offset represents the power offset for the data transmission withrespect to the pilot power. The WTRU then applies the measurement poweroffset (e.g., in the linear domain) to each channel estimate to obtainthe correct effective channel estimate. The concept may be furtherdetailed as follows:

${\hat{h}}_{eff} = {\sum\limits_{l = 1}^{L}{\Gamma_{l}{\hat{h}}_{l}}}$

where Γ₁ is the measurement power offset for the 1^(th) serving HS-DSCHcell (e.g., for 1=1, this corresponds to the serving HS-DSCH cell; 1=2corresponds to the secondary serving HS-DSCH cell), ĥ₁ is the channelestimate for the 1^(th) cell (based on the pilot signal only), andĥ_(eff) is the resulting effective channel estimated.

In another solution, the WTRU assumes for detection that the samedata-to-pilot power offset is used throughout the cells in the servingHS-DSCH cell set. While this may lead to potentially non-optimalreception performance at the WTRU for the soft combining approach, thenetwork may control the WTRU performance by determining on its own therelative power of the data signal versus the pilot signal on each cell.

The network, based on the CQI information it receives from the WTRU,determines the modulation coding set (MCS), the amount of data, and thepower. To ensure optimal detection performance the network may use thesame data-to-pilot power and MCS for all cells transmitting the data tothe WTRU (so that the WTRU derives the optimal filter weights or RAKEfingers). This has the advantage of not requiring additional signalingfrom the network. A single HS-SCCH may be used (e.g., from the servingHS-DSCH cell). This also allows two forms of WTRU receiverimplementation: chip-level equalization and symbol-level combining(e.g., at the HARQ level).

Alternatively, the network may use the same data-to-pilot power andcoded data for all cells, but potentially use a different modulation andcoding scheme (i.e., different RV). This approach has the advantage ofnot requiring additional signaling for the data-to-pilot power offset.The different MCS needs to be signaled to the WTRU (via one HS-SCCH percell). This allows only one form of WTRU implementation: symbol-levelcombining (e.g., at the HARQ level).

Discontinuous downlink reception (DRX) is a continuous packetconnectivity (CPC) feature aimed at WTRU power saving while maintainingWTRU data connectivity. In DRX mode, the WTRU is allowed to receivedownlink data discontinuously according to a preconfigured DRX receptionpattern. In multi-carrier (DC-HSDPA or 4C-HSDPA) realization,implementation of DRX is straightforward, because the same receptionpattern may be used for all cells involved in the transmission. This isfeasible because the cells are assumed belong to the same Node B, andtherefore all the related downlink transmissions may be synchronized.

In multiple point transmission, particularly for inter-Node Bdeployment, the cells in operation may not be synchronized due to theasynchronous nature of the UMTS network. Therefore, the DRX relatedprocedures, such as DRX activation or deactivation, may need to bemodified to accommodate the inter-site deployment requirement.

To maximize the power saving benefit for users, the DRX operations inboth the primary serving cell and the secondary (assistive) serving cellmay be coordinated, such that the reception patterns used by the twocells are aligned in time as much as possible. The same set of DRXparameters or just one set of DRX parameters, such as the DRX cycle, areconfigured in both cells. By engaging the radio interfacesynchronization procedure, the Connection Frame Numbers (CFNs)associated with the transmission of a F-DPCH for both cells may bealigned with a certain level of accuracy. By using this aligned CFN, acontrol algorithm may be designed to generate coordinated downlink DRXreception patterns for both cells. Due to potential variation of thetiming relation of the F-DPCH and HS-SCCH radio frames at differentcells, an additional time adjustment procedure may be used to align thetwo reception patterns.

For example, denote the time difference of the F-DPCH and the HS-SCCH asτ_(DRX0) for the primary serving cell, and τ_(DRX1) for the secondaryserving cell. When the network configures the timing offset parameter,UE_DTX_DRX_Offset, it is required to set it differently for the twoserving cells. More specifically, the relation of the two timing offsetparameters should satisfy the following:

(UE_DTX_DRX_Offset0−UE_DTX_DRX_Offset1)=(τ_(DRX1)−τ_(DRX0))

Note that (τ_(DRX1)−τ_(DRX0)) should be expressed in terms of subframesand rounded to the nearest integer.

For the primary serving cell, the HS-SCCH reception pattern is the setof subframes whose HS-SCCH DRX radio frame number (CFN_DRX) and subframenumber (S_DRX) verify:

((5×CFN_DRX0−UE_DTX_DRX_Offset0+S_DRX0)MOD UE_DRX cycle)=0

where CFN_DRX0 is for the primary serving cell and is the radio framenumber of the HS-SCCH associated with the corresponding F-DPCH radioframe, which is aligned between the two serving cells via the radiointerface synchronization procedure. S_DRX0 is the HS-SCCH subframenumber for the primary serving cell among a radio frame, ranging from 0to 4. The UE_DRX cycle is a parameter configured by higher layers thatspecifies the repetition cycle of the HS-SCCH reception pattern.

For secondary serving cell, the HS-SCCH reception pattern is the set ofsubframes whose HS-SCCH CFN_DRX and S_DRX verify:

((5×CFN_DRX1−UE_DTX_DRX_Offset1+S_DRX1)MOD UE_DRX cycle)=0

where CFN_DRX1 is for the secondary serving cell and is the radio framenumber of the HS-SCCH associated with the corresponding F-DPCH radioframe, and S_DRX1 is the HS-SCCH subframe number for the secondaryserving cell.

As an alternative solution, the network may configure an additionaltiming offset parameter as calculated by:

UE_DRX_Offset=UE_DTX_DRX_Offset0−UE_DTX_DRX_Offset1+(τ_(DRX0)−τ_(DRX1))

This time offset parameter is then applied to calculation of thereception pattern only on the secondary serving cell as follows:

((5×CFN_DRX1−UE_DTX_DRX_Offset1−UE_DRX_Offset+S_DRX1)MOD UE_DRX cycle)=0

In this case, UE_DTX_DRX_Offset0 and UE_DTX_DRX_Offset1 may beconfigured independently by the individual Node Bs.

When DTX mode is activated, the Node Bs in the multipoint operation willperform transmission according to the reception patterns describedabove, respectively for primary and secondary serving cells.

At the WTRU, because the reception patterns are aligned or nearlyaligned as result of the timing adjustment procedure, the WTRU onlyneeds to implement a common state machine that calculates one set ofreception patterns according to the timing counter provided in either ofcells. Once the state machine determines that it is the time interval towake up the WTRU, it starts monitoring HS-SCCHs from both cells forpotential data reception. To avoid potentially missing the datatransmission because of a slight residual offset between the receptionpatterns for different cells, the WTRU may monitor one or a few moreadditional subframes around the receiving interval. Alternatively, theWTRU may ensure that the full HS-SCCH of the cell that is slightlyoffset is monitored, even though according to the formula above, theHS-SCCH monitoring of the other cell has been completed and the WTRUshould turn off the receiver.

An example of aligning the reception patterns is shown in FIG. 13, wherethe parameters are set as: UE_DRX_cycle=4, τ_(DRX0)=1 subframe,τ_(DRX1)=2 subframes, and the timing offset parameters should satisfythe constraint:

(UE_DTX_DRX_Offset0−UE_DTX_DRX_Offset1)=1

In another solution, the network will not maintain multiple DRXreception patterns for a multipoint transmission or attempt tosynchronize them. Instead, only one DRX reception pattern is determinedby using the set of counters or parameters configured for one cell. Forexample, a DRX reception pattern is determined by the existing rules inthe 3GPP standard, using the timing parameters from the primary servingcell. For the DRX operation of the other cells in the multipointtransmission, the corresponding wakeup interval for transmission for acell is determined by finding the subframes that overlap with theprimary reception pattern.

Due to the asynchronous nature between cells, it is possible that onlypart of a subframe is overlapped with the primary reception pattern andpossibly two consecutive subframes may fall into the same wakeupinterval. In this case, rules are defined to make unique selection ofthe subframes with a number of options: the subframe with the mostoverlap time with a wakeup interval defined by the reception pattern;the first subframe that overlaps with a wakeup interval defined by thereception pattern; or the last subframe that overlaps with a wakeupinterval defined by the reception pattern.

The WTRU maintains one state machine that generates the receptionpattern. For the data reception from the other serving cells, itmonitors HS-SCCHs in the subframes that satisfy the rules describedabove.

As an example, the HS-SCCH reception pattern is the set of subframeswhose HS-SCCH CFN_DRX and S_DRX verify:

((5×CFN_DRX−UE_DTX_DRX_Offset+S_DRX)MOD UE_DRX cycle)=0

Then in the multipoint HSDPA transmission mode, the HS-SCCH receptionpattern is generated only for the primary serving cell. The HS-SCCHreception subframes for the other serving cells are derived from thispattern by finding the last one, for example, that overlaps with asubframe timing interval defined by the HS-SCCH reception pattern.

Either for the independent or coordinated DRX operation described above,it may be beneficial if all cells in transmission enter into the DRXmode concurrently, because the entire radio front end at the WTRU may bestopped during the inactive period to maximally claim the power savingbenefit. A control mechanism may be provided that enables coordinatedactivation or deactivation of the DRX mode among the cells.

The Node B at either of the cells may act on its own to initiateactivation or deactivation of the DRX operation based on the informationit has perceived regarding the data traffic or WTRU operating status.Once the Node B scheduler decides to activate or deactivate the DRX modefor a WTRU, it sends an (de)activation HS-SCCH order to the WTRUdirectly without any supervision from the RNC.

A notification is signaled concurrently or afterwards to the serving RNC(SRNC) via the Iur interface, to inform the RNC about the DRXactivation/deactivation. Upon receiving this notification, the SRNC mayfurther send a command to the Node B(s) at other cell(s) involved in themultipoint transmission. This command may include an order that directsthe Node B to start (or stop) the DRX mode, and/or optionally the timinginformation (e.g., specified by a CFN) that tells the Node B when toactivate or deactivate DRX mode.

The Node B that receives the DRX activation/deactivation command fromthe SRNC signals a DRX activation/deactivation order over the HS-SCCH tothe WTRU, allowing the downlink transmission carried over this servingcell to enter (or quit) the DRX mode. Alternatively, if a common DRXstate is implemented in the WTRU and the order has been received by thefirst cell, the Node B does not have to send another DRX order. Uponnotification of the DRX activation/deactivation from the SRNC or theother Node B, the Node B may simply start or stop DRX operation.

FIG. 14 is a flow diagram of the notification-based DRXactivation/deactivation procedure 1400. In the procedure 1400, a WTRU1402 communicates with a Node B for the primary serving cell 1404 and aNode B for the secondary serving cell 1406. The Node Bs 1404 and 1406communicate with a serving RNC (SRNC) 1408.

The WTRU 1402 receives a HS-SCCH order for activation or deactivation ofthe primary cell from the Node B 1404 (step 1410). The Node B 1404 sendsa corresponding DRX activation or deactivation notification to the SRNC1408 (step 1412). The SRNC 1408 sends a DRX activation or deactivationcommand to the Node B 1406 (step 1414). The Node B 1406 sends a HS-SCCHorder for activation or deactivation order for the secondary cell to theWTRU 1402 (step 1416).

With the notification-based DRX activation/deactivation, latency willlikely exist in the DRX activation/deactivation over different cells. Toallow all the cells to enter (or quit) the DRX mode simultaneously, theinitiating Node B may send the notification to the SRNC or the otherNode B first (e.g., prior to sending an order to the WTRU). In thenotification message, the initiating Node B may include timinginformation of the activation/deactivation. For example, the initiatingNode B may specify the CFN that it is going to signal the HS-SCCH orderto the WTRU.

Alternatively, a fixed delay from the reception of the notification tothe activation/deactivation may be specified. This notification messageis forwarded to the other Node Bs in the multipoint transmission, suchthat they can prepare for the activation/deactivation. At the specifiedtiming defined by the timer or by the specified CFN, one of the Node Bs(e.g., the initial or primary Node B) may send the HS-SCCH order to theWTRU to start (or stop) the DRX mode for all the serving cells.Optionally, the other serving Node Bs may also send the same order overtheir corresponding downlink to improve reliability.

FIG. 15 is a flow diagram of a DRX activation/deactivation notificationprocedure 1500 including a timer. In the procedure 1500, a WTRU 1502communicates with a Node B for the primary serving cell 1504 and a NodeB for the secondary serving cell 1506. The Node Bs 1504 and 1506communicate with a serving RNC (SRNC) 1508.

The Node B 1504 sends a DRX activation or deactivation notification tothe SRNC 1508, with the notification including timing information (step1510). As noted above, the timing information may include a fixed timeof the activation or deactivation command or a delay value indicating arelative time until the sending of the activation or deactivationcommand. The SRNC sends a DRX activation or deactivation command to theNode B 1506 based on the timing information (step 1512). Also based onthe timing information, the Node B 1504 sends a HS-SCCH order foractivation or deactivation of both the primary cell and the secondarycell to the WTRU 1502 (step 1514).

In handshake-based DRX activation/deactivation, the initiating Node Bsends a DRX activation/deactivation request to the SRNC, instead of anotification message as described above. The SRNC decides whether therequest is granted or not. The SRNC may evaluate the request based onthe higher layer traffic condition and buffer status, together with theWTRU operating conditions it received through the WTRU measurementreport. Once the SRNC decides that the request is granted, it sends agrant message to the initiating Node B, which may also include timinginformation specified by a CFN to inform the Node B when to transmit theHS-SCCH order to the WTRU. In the meantime, the same message or asimilar message is sent to other Node Bs in the multipoint transmissionto initiate the DRX activation/deactivation on other serving cells. Ifthe SRNC decides not to grant the request, it may send a NACK message tothe initiating Node B to invalidate the request. Or optionally, the SRNCdoes not respond to the request at all. If a timer set at the Node Bexpires before it receives the grant from SRNC, the Node B knows therequest was not granted.

FIG. 16 is a flow diagram of the handshake-based activation/deactivationprocedure 1600. In the procedure 1600, a WTRU 1602 communicates with aNode B for the primary serving cell 1604 and a Node B for the secondaryserving cell 1606. The Node Bs 1604 and 1606 communicate with a servingRNC (SRNC) 1608.

The Node B 1604 sends a DRX activation or deactivation request to theSRNC 1608 (step 1610). The SRNC 1608 sends a DRX activation ordeactivation grant to the Node B 1604 (step 1612) and sends acorresponding DRX activation or deactivation command to the Node B 1606(step 1614). It is noted that steps 1612 and 1614 may occursimultaneously or in a reversed order (so that step 1614 happens beforestep 1612) without affecting the operation of the procedure 1600. Afterreceiving the grant from the SRNC 1608, the Node B 1604 sends a HS-SCCHorder for activation or deactivation of both the primary cell and thesecondary cell to the WTRU 1602 (step 1616).

In step 1616, only the initiating Node B 1604 sends the HS-SCCH order tothe WTRU 1602, which activates or deactivates DRX operation for allserving cells in the multipoint operation. Optionally, the separateHS-SCCH orders may be sent by other Node Bs, possibly with an intentionto have the DRX operation being activated or deactivated at a slightlydifferent timing. This timing difference may be controlled by the SRNC1608 via timers specified in the grant messages addressed to thedifferent Node Bs.

The DRX activation or deactivation may be initiated by the serving RNConly. The RNC makes the decision based on the traffic conditions and theNode B scheduling status it perceives. At the time the RNC decides toactivate or deactivate the DRX mode for a WTRU, it signals all relatedNode Bs in the multipoint transmission with a command message thatspecifies the action to be taken and the time of the execution. Uponreceiving the command message, the Node Bs send either a single orseparated HS-SCCH orders to the WTRU to complete the action.

FIG. 17 shows the RNC controlled DRX activation/deactivation procedure1700. In the procedure 1700, a WTRU 1702 communicates with a Node B forthe primary serving cell 1704 and a Node B for the secondary servingcell 1706. The Node Bs 1704 and 1706 communicate with a serving RNC(SRNC) 1708.

The SRNC 1708 sends a DRX activation or deactivation command to the NodeB 1704 (step 1710) and to the Node B 1706 (step 1712). It is noted thatsteps 1710 and 1712 may occur simultaneously or in a reversed order (sothat step 1712 happens before step 1710) without affecting the operationof the procedure 1700. After receiving the command from the SRNC 1708,the Node B 1704 sends a HS-SCCH order for activation or deactivation ofboth the primary cell and the secondary cell to the WTRU 1702 (step1714).

Alternatively, DRX mode may only be allowed in the primary serving cell.The Node B that serves the primary serving cell may communicate the DRXactivation/deactivation with the SRNC either by notification-based orhandshake-based methods as described above. When the Node B that servesas the secondary serving cell receives the DRX activation command (ornotification) from the SRNC, it may signal a cell deactivation orderover the HS-SCCH to the WTRU to deactivate the entire transmission fromthe secondary serving cell during the DRX operation mode. When the NodeB that serves as the secondary serving cell receives the DRXdeactivation command from the SRNC, it may signal a cell activationorder over the HS-SCCH to the WTRU to re-activate the secondary servingcell. Alternatively, when the SRNC receives the DRX activationnotification for the Node B that serves as the primary serving cell, itsimply stop sending data to the secondary Node B. Therefore, thesecondary serving cell operates as if it is deactivated, so that WTRUdoes not need to monitor the transmission from the secondary servingcell during the DRX mode.

Network behavior upon the DRX activation or deactivation is describedbelow. With the multipoint transmission operating in inter-Node B modeor inter-site mode, there may be more than one MAC entity residing atdifferent Node Bs. Thus, the serving RNC needs to split the data fromthe higher layers and dispatch the data to each of the MAC buffers. Toavoid unnecessary RLC retransmissions, the serving RNC monitors thescheduling activities of each Node B and distributes the appropriateamount of data to them.

Upon receiving the DRX activation notification from the initiating NodeB, the SRNC is required to stop distributing any data to the MAC bufferat the Node B, or reduce the data size to a level that may be handled bythe DRX mode. The remaining data traffic from higher layers, if there isa large amount, is directed to the MAC(s) of the other serving cells. Inthis case, the action to activate DRX for the other serving cell may bedeferred until the data is sent.

Because of the latency in receiving the activation notification message,the data splitting function at the SRNC may still distribute some datato the initiating Node B after it enters DRX mode. This data may take anexcessive amount of time to transmit, due to the inactive transmissionstatus of that Node B. In this case, the SRNC may re-distribute the samedata to other Node Bs if it can foresee what is happening after itreceives the activation notification. At the initiating Node B, it isbetter to flush its MAC buffer and remain in DRX mode.

For the handshake-based or RNC-controlled activation procedures, theserving RNC controls everything, therefore the data splitting orredirecting issue is of less concern.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element may be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A wireless transmit/receive unit (WTRU)comprising: a processor; and a receiver; and the receiver configured toreceive a first physical downlink control channel (PDCCH) indicating atransmission by a first cell and to receive a second PDCCH indicating atransmission by a second cell, wherein the first cell and the secondcell have different carrier frequencies; the receiver is configured toreceive a first physical downlink control channel (PDSCH) of the firstcell based on the first PDCCH and to receive a second PDSCH of thesecond cell based on the second PDCCH, wherein the first PDSCH includessame data as the second PDSCH; and the processor is configured torecover the same data using at least the received first PDSCH or thereceived second PDSCH.
 2. The WTRU of claim 1 wherein the first PDCCHand the second PDCCH are received from different cells.
 3. The WTRU ofclaim 1 wherein the first cell and the second cell originate fromdifferent network nodes.
 4. The WTRU of claim 3 wherein the first cellis associated with a first radio network terminal identifier and thesecond cell is associated with a second RNTI, wherein the first RNTI andthe second RNTI are different.
 5. The WTRU of claim 1 wherein the firstPDSCH and the second PDSCH have different modulations.
 6. The WTRU ofclaim 1 wherein the first PDSCH and the second PDSCH have differentredundancy versions.
 7. The WTRU of claim 1 wherein the first PDSCH andthe second PDSCH have different precoding weights.
 8. The WTRU of claim1 wherein there first PDCCH includes an indicator of a cell of the firstPDSCH.
 9. The WTRU of claim 1 wherein the first PDSCH and the secondPDSCH are transmitted at different times.
 10. A method for use in awireless transmit/receive unit (WTRU), the method comprising: receivinga first physical downlink control channel (PDCCH) indicating atransmission by a first cell and to receive a second PDCCH indicating atransmission by a second cell, wherein the first cell and the secondcell have different carrier frequencies; receiving a first physicaldownlink control channel (PDSCH) of the first cell based on the firstPDCCH and to receive a second PDSCH of the second cell based on thesecond PDCCH, wherein the first PDSCH includes same data as the secondPDSCH; and recovering the same data using at least the received firstPDSCH or the received second PDSCH.
 11. The method of claim 10 whereinthe first PDCCH and the second PDCCH are received from different cells.12. The method of claim 10 wherein the first cell and the second celloriginate from different network nodes.
 13. The method of claim 10wherein the first cell is associated with a first radio network terminalidentifier and the second cell is associated with a second RNTI, whereinthe first RNTI and the second RNTI are different.
 14. The method ofclaim 10 wherein the first PDSCH and the second PDSCH have differentmodulations.
 15. The method of claim 10 wherein the first PDSCH and thesecond PDSCH have different redundancy versions.
 16. The method of claim10 wherein the first PDSCH and the second PDSCH have different precodingweights.
 17. The method of claim 10 wherein there first PDCCH includesan indicator of a cell of the first PDSCH.
 18. The method of claim 10wherein the first PDSCH and the second PDSCH are transmitted atdifferent times.